Which social media app has a ghost as its mascot?
The social media app using a ghost as its mascot (and also app icon) would be Snapchat. It is a social media and messaging platform available on modern mobile devices, like iPhones and Android-based devices.
Snapchat used to exchange text and media messages called Snaps with other users. The catch is, these messages are meant to automatically delete unless someone deliberately chooses to save a Snap to their device.
Since media messages are the unique point of Snapchat, it is mostly known for it's wide variety of advanced multimedia filters and effects. Examples would include cartoon 3D style filter, polaroid-like lenses and frames, gender swap filters, and many more.